Papermaking headbox with adjustable hydraulic nozzle and slice

ABSTRACT

AN ADJUSTABLE PRESSURE NOZZLE FOR THE DELIVERY OF PAPERMAKING FURNISHES TO FORAMINOUS MEDIA IN THE HIGH SPEED PRODUCTION OF PAPER AND WET LAID NONWOVEN, WHICH ADJUSTABLE PRESSURE NOZZLE IS PROVIDED WITH ARTICULATION IN ITS VARIOUS ROOF SECTIONS AND THROAT. EITHER OR BOTH THE FORMATION ZONE AND THROAT OF THE ADJUSTABLE PRESSURE NOZZLE CAN BE ADJUSTED AND THEREAFTER MAINTAINED IN POSITION WHILE THE CONVERGENCE ANGELES IN THE APPROACH CHANNEL PRECEDING THE THROAT REMAIN ADJUSTALBE BY EMPLOYING PIVOTABLE KNUCKLES BETWEEN THE VARIOUS ROOF SECTIONS, EACH   KNUCKLE BEING CONNECTED TO AN INDIVIDUAL KNUCKLE PIVOT, THE KNUCKLES DOWNSTREAM OF THE APPROACH CHANNEL BEING VERTICALLY ADJUSTABLE; AND BY EMPLOYING AN EXPANSION KNUCKLE UPSTREAM OF THE APPROACH CHANNEL. THE ADJUSTABLE PRESSURE NOZZLE PROVIDES MEANS AND PROCESS WHERBY TENSILE RATIO ADJUSTMENTS ARE CONVENIENTLY AFFECTED DURING PAPER FORMATION WHILE THE FORMATION ZONE LENGTH AND GEOMETRY ARE FIXED.

' Filed April. 5, 1968 Jan. 19, 1971 J. s. AMNEUS ETAL 3,556,935

PAPERMAKING HEAD W ADJU BLE HYDRAULIC N0 E SLIC 2 Sheets-Sheet 1INVENTORS John S. Amneus BY Abdul S. Bohroni l/ A1? MW Z' ATTORNEY Jan.19, 1971 1 J 5 AMNEUS ETAL 3,555,935

PAPERMAKING HEADBOX WITH ADJUSTABLE HYDRAULIQ NOZZLE AND SLICE FiledApril 5, 1968 2 Sheets-Sheet 2 INVENTORS John S. Amneus BY Abdul S.Bohroni ATTORNEY United States Patent 3,556,935 PAPERMAKING HEADBOX WITHADJUSTABLE HYDRAULIC NOZZLE AND SLICE John S. Amneus and Abdul S.Bahrani, Cincinnati, Ohio,

assignors to The Procter & Gamble Company, Cincinnati, Ohio, acorporation of Ohio Filed Apr. 3, 1968, Ser. No. 718,596 Int. Cl. D2lf1/02 US. Cl. 162214 6 Claims ABSTRACT OF THE DISCLOSURE An adjustablepressure nozzle for the delivery of papermaking furnishes to foraminousmedia in the high speed production of paper and wet laid nonwovens,which adjustable pressure nozzle is provided with articulation in itsVarious roof sections and throat. Either or both the formation zone andthroat of the adjustable pressure nozzle can be adjusted and thereaftermaintained in position while the convergence angles in the approachchannel preceding the throat remain adjustable by employing pivotableknuckles between the various roof sections, each knuckle being connectedto an individual knuckle pivot, the knuckles downstream of the approachchannel being vertically adjustable; and by employing an expansionknuckle upstream of the approach channel. The adjustable pressure nozzleprovides means and process whereby tensile ratio adjustments areconveniently effected during paper formation while the formation zonelength and geometry are fixed.

BACKGROUND OF THE INVENTION This invention relates to headboxes for thedelivery of fibrous slurries and papermaking furnishes to foraminousmedia in papermaking and wet-laid nonwoven formation processes. Moreparticularly, the invention relates to headboxes of the hydraulic orpressure nozzle type which are equipped with a. vertically tapered orconverging rectangular passage through which fibrous slurry or furnishpasses, which rectangular passage has one or more means for adjustingits critical geometry to achieve response in paper formationcharacteristics.

Specifically, the invention, described herein in terms of paperprocessing, provides an adjustable pressure nozzle with suitablehydraulic characteristics for high speed paper production wherein meansare provided for adjusting the convergence angles or vertical tapers inthe several nozzle approach channels. The adjustments in the adjustablepressure nozzle can be accomplished during continuous paper formationwhile maintaining desired combinations of nozzle throat clearance andformation zone length. Processes for regulating tensile ratio in paperduring continuous paper formation are also provided.

Papermaking headboxes of considerable complexity have been proposedheretofore for the delivery of papermaking furnishes to Fourdrinierwires and other foraminous media. For example, US. 2,418,600, issued toH. M. Ostertag on Apr. 8, 1947, discloses a headbox having adjustablejoints or knuckles connecting the various sectionsof its roof. Also, US.2,995,485, issued to C. A. Lee on Aug. 8,,1961, discloses a headbox fora paper machine, which headbox is equipped with means for adjusting themachine direction and vertical adjustment of the slice Patented Jan. 19,1971 "ice roof tip in relation to the vertical center line and formationzone of the breast roll.

In spite of the availability of prior art headboxes affording aconsiderable degree of mechanical adjustment, applicants are unaware ofany headbox configuration which affords an adjustable pressure nozzlewith sufficient roof articulation of the proper type to permit anadjustment in nozzle convergence angles while maintaining desiredcombinations of nozzle throat clearance and formation zone length duringcontinuous papermaking operations.

An adjustable pressure nozzle permitting running changes of convergenceangle while maintaining a desired formation zone length and geometry hasbeen found to be quite beneficial in contributing to the formation oflightweight tissue, other papers and wet-laid nonwovens at high machinespeeds. In general, those skilled in the papermaking arts are aware thatthe convergence angles in a pressure nozzle headbox affect the machinedirection alignment or disalignment of fibers deposited during sheetformation. Fibers are aligned by the increased acceleration induced byhigh convergence angles; pressure nozzles having lesser convergenceangles promote random fiber deposition in formation. Fiber alignmentresults in high machine direction tensile, but low cross-machinedirection tensile in paper. Random fiber deposition results in paperexhibiting tensile strengths which are more nearly equal in both themachine nad cross-machine directions. At the same time paper machineoperation at given paper formation speeds, furnish consistencies andbreast roll vacuum conditions requires a commensurate formation zonelength for furnish water drainage and spouting prevention. If theformation zone length can be maintained constant, then convergence angleadjustment will provide ideal tensile control and control response tochanges in furnish freeness.

By means of the convergence angle or vertical taper adjustment theamount and direction of fiber orientation obtained within the adjustablepressure nozzle during continuous papermaking and other wet-laidnonwoven web forming operations is affected. Expressed in another conventional term of the art fiber orientation or alignment controls to alarge degree the machine direction tensile strength to cross-machinedirection tensile strength ratio, or simply the tensile ratio, inwet-laid nonwoven webs and papers.

The most careful calculation of the proper convergence angle, i.e., theangle included between the floor and roof of a pressure nozzle in theapproach channel, to be used in a pressure nozzle can only satisfy oneset of wet-laid nonwoven web, including paper, formation conditions orthe hydraulic equivalent thereof. The adjustable pressure nozzle of thepresent invention affords means whereby the hydraulic characteristics ofa pressure nozzle can be precisely controlled during continuouspapermaking operations to affect fiber orientation.

Although the pressure nozzles heretofore disclosed for use inpapermaking have afforded certain adjustments in their geometry, theirconfiguration and articulation has been such that articulation of theirnozzle adjustments caused changes in either or both their formation zonelength and nozzle throat clearance. The changes in formation zone lengthaccompanying convergence angle changes in these pressure nozzles eitherintroduced such gross changes in formation that precise tensile ratiocontrol was diificult to achieve or caused paper breaks necessitatingpaper machine shutdown in order to adjust to new conditions.

SUMMARY OF THE INVENTION Applicants discovered and developed the presentadjustable pressure nozzle configuration in order to provide a selectedformation zone length and nozzle throat configuration in conjunctionwith means for tensile strength response adjustments in a pressurenozzle which could provide the desired adjustment advantages duringcontinuous paper formation. In this way applicants have provided anadjustable pressure nozzle which is adapted to the fine hydrauliccontrol of paper formation which is difiicult or impossible to achievewithout the continuity of response afforded by adjustment duringcontinuous paper formation.

Briefly stated, in accordance with one embodiment of the invention,there is provided an adjustable pressure nozzle for the delivery offibrous slurry onto a moving foraminous media in a papermaking machine,which ad .justable pressure nozzle defines a vertically convergingrectangular passage comprised essentially of an approach channel, anozzle throat and a formation zone. The adjustable pressure nozzle isprovided with means for adjusting the convergence angles in its approachchannel while maintaining its nozzle throat and formation zone in afixed configuration, preferably after initial adjustment. The roof ofthe pressure nozzle is provided with an expansion joint to allowmaintaining the slice roof tip and nozzle throat in a desired position,while knuckle pivots and adjustment jacks provide for convergence angleand nozzle throat clearance adjustments. An eccentric lever and a camlift, all providing an eccentric cam pivot, provide means for eitherinitial or later desired adjustment of formation zone length andclearance between the slice roof and Fourdrinier wire.

Accordingly, it is an object of this invention to overcome theaforementioned problems and disadvantages while providing an adjustablepressure nozzle equipped with meaningful and precisely adjustablearticulatory means.

It is another object of this invention to provide an adjustable pressurenozzle having adjustments whereby the alignment of the apermaking fiberscan be controlled in the pressure nozzle and at the formation zone toresult in paper which more nearly utilizes the ultimate tensile strengthproducing capability of a given paper furnish in both the machine andcross-machine directions.

A further object of this invention is to provide a papermaking headboxof the nozzle type which provides for maintaining a chosen nozzle throatclearance and formation zone length while enabling running changes inthe convergence angle of the nozzle approach channel.

Yet another object of this invention is to provide processes for tensileratio control during continuous paper formation.

BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes withclaims particularly pointing out and distinctly claiming the subjectmatter regarded as forming the present invention, it is believed thatthe invention will be better understood from the following descriptiontaken in connection with the accompanying drawings in which like numbersrefer to like nozzle elements and features:

FIG. 1 is a cross-sectional side elevation of a preferred embodiment ofthe present papermaking headbox con structed in accordance with thisinvention with the objective of showing the essential features thereof;and

FIG. 2 is a perspective view of the preferred embodiment of thepapermaking headbox illustrated in FIG. 1 with parts cut away in orderto facilitate the illustration of important details.

t 4 DESCRIPTION OF THE PREFERRED EMBODIMENTS In describing the preferredembodiment of the invention illustrated in the drawings, specificterminology will be resorted to for the sake of clarity. It is notintended, however, to be limited to the specific terms so selected, andit is to be understood that each specific term includes all technicalequivalents thereof which operate in a similar manner to accomplish asimilar purpose.

Referring now to the specific embodiment of the papermaking headbox oradjustable pressure nozzle selected for illustration in FIGS. 1 and 2,the number 10 designates generally a apermaking headbox of theadjustable pressure nozzle type as contemplated by the presentinvention. Papermaking headbox 10 is equipped with headbox inletenclosure 11 for introducing apermaking furnish or fibrous slurry intonozzle entry channel 18. Back channel roof 19 of back channel 22 can beadjusted and fixedly positioned, by means of shims and fastening meansduring erection and subsequently during cessation of paper formation, toalfect the relative angular convergence and position of back channelroof 19 with respect to back channel floor 20. Thereafter the positionof back channel roof 19 remains fixed during paper formation. Adjustmentmeans, further detailed below, are provided for effecting runningadjustments of the position of slice roof 29 and nozzle throat 28, inthe machine and vertical directions, with resepct to apron 26 andFourdrinier wire 59 on breast roll 58. Slice roof tip 30 can also bevertically adjusted along its length by means of slice micro-jacks 57 ofwhich several are provided in spacing along the length of slice roof tip30, only two of which are illustrated in FIG. 2 to avoid confusion, toprovide desired profile control of the paper sheet as formed.

"FIGS. 1 and 2 illustrate a papermaking headbox 10 in which theconvergence angle or taper in approach channel 24, angle channel 27 andformation zone 31 can all be adjusted and maintained in positionindependent from the machine direction position of slice roof tip 30 andnozzle throat 28, within the adjustment travel limits provided and whilecontinuously forming a sheet of paper. It will be noted that bothapproach channel 24 and angle channel 27, although independentlyarticulated, are in effeet a single approach channel in that theyprovide for the vertical convergence of furnish toward nozzle throat 28.'Other embodiments of the present adjustable pressure nozzle could beprovided with a single approach channel provided with knuckle andexpansion articulation in its roof. The adjustment means provided makepossible the maintenance of a desired length in formation zone 31,extending from the end of apron 26 to slice roof tip 30 while adjustingthe vertical convergence or taper in approach channel 24 and anglechannel 27.

Papermaking headbox 10 includes means for distributing a paper furnishwithin nozzle entry channel 18 by means of the holes in distributorplate 15. Adjustment of the furnish distribution and velocity throughdistributor plate 15 and across the width of nozzle entry channel 18 isfacilitated by adjustable bow plate 12 which can be adjusted and fixedin position to equalize furnish flow across the width of distributorplate '15 and nozzle entry channel 18. Distributor plate 15 is equippedwith headbox inlet hinge 13 and headbox inlet latch 14. Distributorplate gaskets 16 are also provided to effect a 'seal between distributorplate 15 and nozzle entry plate expansion knuckle 33, which providesmachine direction expansion for approach roof 23 and angle roof 25during convergence angle adjustment, and with first approach knuckle 35.There is also provided a second approach knuckle 38. Breast roll liftgear motor 32, although not essential to the present invention, isidentified for the sake of completeness and acts through a pulley-cablearrangement, not illustrated, to raise and lower breast roll 58.

Distributor plate imparts a controlled amount of vortex disturbance tothe fibers in the papermaking furnish during flow therethrough. Nozzleentry plate 17 is operative as a bearing and sealing surface againstdistributor plate 15. The seal is made complete by distributor plategasket 16. Several back channel roof crossbearns 61 are provided tosupport and make rigid back channel roof 19.

Headbox inlet enclosure 11 is hingably mounted to bear against nozzleentry plate 17. The hinge support of headbox inlet enclosure 11 isprovided by headbox inlet hinge 13 and headbox inlet latch 14. Headboxinlet enclosure 11 and distributor plate 15 can be rotated downwardly onheadbox inlet hinge 13, after loosening headbox inlet latch 14, toexpose the mouth of back channel 22, nozzle entry channel 18, forinspection and cleaning.

Entering into the present adjustable nozzle proper, the first section,nozzle entry channel 18, comprises a vertically'converging or taperingchannel providing transition from distributor plate 15 toback channel22. Alternately, the entire transition may be made along the totallength of back channel 22, and nozzle entry channel 18 can beeliminated. Although nozzle entry channel 1 8 and back channel 22 areillustrated in the embodiment of the invention depicted in FIGS. 1 and 2as being bounded or defined by straight lines, back channel floor 20 andback channel roof 19, which define the contour of back channel 22 andnozzle entry channel 18, can take the form of hyperbolic curves or othercurved shapes which are conventionally used in papermaking headboxes andin the hydraulic arts. Curved shapes can also be employed in the otherroof and floor elements of head box 10.

Back channel roof 19 is positionable by virtue of nozzle entry plate 17bearing against the face of distributor plate 15 at its entry and bymeans of first approach knuckle 35 and expansion knuckle 33 at itsdownstream end. As stated before, back channel roof 19 is adjustable inthe illustrated embodiment by means of shims and fastening meansincluding bolts, but is held in fixed position during continuouspapermaking operation. In other embodiments of the present adjustablepressure nozzle, back channel roof 19 could be articulated in the mannerof approach roof 23 and angle roof 25. The downstream end of backchannel roof 19 is held upwardly in position against expansion knuckle33 by expansion knuckle tension rods 34. It will be understood by thoseskilled in the art that although FIGS. 1 and 2 for clarity show one of agiven articulation or means of adjustment, there will be providedmultiple means where necessary across the width of the adjustablepapermaking nozzle. For example, twenty of the expansion knuckle tensionrods 34 are provided across the width of the specific embodiment ofpapermaking headbox 10 illustrated in FIGS. 1 and 2.

Expansion knuckle 33 and first approach knuckle 35 are provided withfurther articulation and adjustability by means of their support onfirst approach knuckle pivot 37. First approach knuckle pivot 37 andfirst approach 'knuckle crossbeam 36 serve as supports, acting throughfirst approach knuckle 35, for the entry or upstream end of approachroof 23. Approach roof 23 is supported at its'downstream end by secondapproach knuckle 38, mounted on second approach knuckle crossbeam 39.Second approach knuckle 38 also supports the entry or upstream end ofangle roof whose downstream end is supported by outer throat knuckle 44.Alternately, outer throat knuckle 44 can be an expansion knuckle similarto expansion knuckle 33. Outer throat knuckle 44 also serves togetherwith the downstream end of apron 26 to partially define the nozzlethroat 28 at the entry to formation zone 31 above and on Fourdrinierwire 59 supported by breast roll 5-8. Formation zone 31 is furtherenclosed and defined by slice roof 29. The entire headbox is supportedon mounting support 63, and back channel floor 20 is supported on andmade stable by multiple back channel floor crossbearns 21.

Second approach knuckle pivot 40 and second approach knuckle 38 togetherwith outer throat knuckle 44 are provided for the articulation ofapproach roof 23 and angle roof 25. The actual positioning andadjustment of angle roof 25 is accomplished by means of approachadjustment jack 41 and throat adjustment jack 46. Approach adjustmentjack 41 is also used to position the downstream end of approach roof 23.The downstream end of back channel floor 20 is connected to apron 26,which is mounted in close proximity to Fourdrinier wire 59 on theperiphery of breast roll 58. Throat adjustment slide and bushing 47,actuated by throat adjustment jack 46, together with throat knucklepivot 45 is used to adjust and articulate throat knuckle '42 and nozzlethroat 28. The clearance and adjustment of nozzle throat 28 is made morerigid by throat knuckle crossbeam -43. Throat knuckle 42 is furtheradjusted and held in the machine direction by slice overhang adjustmentjack acting through slice overhang adjustment rod 49, slice overhangadjustmentpivot 48 and throat knuckle crossbeam 43. Alternately, sliceoverhang adjustment jack 50 acting through slice overhang adjustment rod49 can be pivotally attached to slice roof tip 30. In this attachmentposition the length of formation zone 31 can be fixed while nozzlethroat 28 remains adjustable. In the attachment position illustrated inFIGS. 1 and 2, the length of formation zone 31 is adjusted by alteringthe machine direction of throat knuckle 42. In another alternateembodiment of the present adjustable pressure nozzle, nozzle throat 2 8and formation zone 31 can be provided in fixed configuration whileretaining articulatory means in approach roof 23 and angle roof 25.

Eccentric lever 51 and eccentric pivot 64 is used to position slice roof29. Also used in this positioning are eccentric slice lift cam 52, slicelift jack 54, eccentric slice lift cam housing 53 and slice roofcrossbeam 55. These elements provide machine direction articulation andvertical adjustment for slice roof tip 30. Rotation of slice micro-jackadjustment knob 56 further positions slice roof tip 30 by actuatingslice micro-jack 57 and affecting the positioning of slice roof tip 30through slice roof tip pivot 60. Although only one slice micro-jack 57is shown in FIG. 1 and two in FIG. 2 to avoid confusion, it will beunderstood that multiple slice micro-jacks 57 and slice micro-jackadjustment knobs 56 are provided along the length of slice roof tip 30.These multiple slice microjacks 57 provide means whereby slice roof tip30 can be profiled to promote evenness in basis Weight across the widthof deckle of the paper product. Slice roof crossbeam splash guard 62extends downwardly from the top of slice roof crossbeam and directssplash onto the top of slice roof 29 Where it does not interfere withthe structure of the paper being formed.

In operation, papermaking furnish is pumped into headbox 10 throughheadbox inlet enclosure 11 and distributor plate 15 and proceeds intonozzle entry channel 18. The papermaking furnish then proceeds throughback channel 22 and downstream through approach channel 24 to anglechannel 27. From angle channel 27 the furnish passes through nozzlethroat 28 and proceeds underneath slice roof 29 where the fibers itcontains are deposited on an instantaneous section of Fourdrinier wire59 in formation zone 31 to form paper as Fourdrinier wire 59 proceedsaround breast roll 58. Adjustment in headbox 10 can be made in themanner heretofore described in relation to the various parts of headbox10.

In the operation of headbox 10 to regulate tensile ratio in paper,applicants practice a process wherein they adjust slice overhangadjustment jack 5 to achieve an initial formation zone length information zone 31. After the initial adjustment of formation zonelength, the machine direction position of slice roof tip 30, and thuslythe formation zone length, is fixed in position. Thereafter the tensileratio of the paper formed during continuous paper formation is regulatedby adjusting the convergence angle in the approach channel, which in theadjustable pressure nozzle embodiment illustrated in FIGS. 1 and 2 iscomprised of approach channel 24 and angle channel 27.

In further methods of operation, applicants can first adjust the nozzlethroat clearance in the adjustable pressure nozzle to achieve an initialfibrous slurry velocity through nozzle throat 28 and in formation zone31. Fixing the nozzle throat clearance will then have the effect offixing both the nozzle throat 28 and formation zone 31 configurationwhile the tensile ratio of the paper formed during continuous paperformation can be adjusted as stated above. Alternately, applicants mayadjust and then fix both the nozzle throat clearance and the formationzone length prior to regulating the tensile ratio of the paper formedduring continuous papermaking operations by adjusting the convergenceangle in the approach channel.

Headbox is especially adapted for use in the manufacture of lightweighttissue where it is desired to control the machine direction-crossmachine direction tensile ratio during continuous papermakingoperations. Headbox 10 is particularly advantageous in that theconvergence angles in approach channel 24 and angle channel 27 can beadjusted while paper is being formed without altering the position of orclearance in nozzle throat 28 after initial adjustment. Therefore, thefurnish velocity through nozzle throat 28 and the geometry of formationzone 31 can be maintained while eflecting changes in tensile ratio, andit becomes clear from the foregoing detailed explanation that theessence of applicants invention is the provision of an adjustablepressure nozzle wherein formation zone elements can be fixed in positionwhile effecting adjustments in the approach channel convergence anglesduring continuous papermaking operations.

It is to be understood that the embodiment of the invention illustratedin FIGS. 1 and 2 is to be taken as a preferred embodiment. Variouschanges may be made in the shape, size and arrangement of the severalapparatus elements without departure from the invention. For example,equivalent elements may be substituted for those illustrated anddescribed herein, and parts may be re versed, while certain features ofthe invention may be utilized independently of the use of otherfeatures, all without departing from the spirit or scope of theinvention defined in the appended claims. Papermaking headboxes may beconstructed in accordance with this invention from the conventionallyused metals and plastics having the necessary rigidity and corrosioncharacteristics for use in such a device.

Having thus described the invention, what is claimed is:

1. The process of regulating tensile ratio in paper dur ing continuouspaper formation by the delivery of fibrous slurry onto a movingforaminous medium through an adjustable pressure nozzle having anapproach channel, a nozzle throat and a formation zone capable ofadjustment, which process comprises:

(a) adjusting the adjustable pressure nozzle machine direction positionto achieve an intial formation zone length,

(b) fixing the machine direction position of the slice roof tip definingthe downstream end of said formation zone, and thereafter (c) regulatingthe tensile ratio of the paper during continuous paper formation byadjusting the convergence angle in the approach channel without alteringsaid formation zone length.

2. The process of regulating tensile ratio in paper during continuouspaper formation by the delivery of fibrous slurry onto a movingforaminous medium through an adjustable pressure nozzle having anapproach channel, a nozzle throat and a formation zone capable ofadjustment, which process comprises:

(a) adjusting the nozzle throat clearance in the adjustable pressurenozzle to achieve an initial fibrous slurry velocity in the formationzone,

(b) fixing the nozzle throat machine direction position and clearance,and thereafter (c) regulating the tensile ratio of the paper duringcontinuous paper formation by adjusting the convergence angle in theapproach channel without altering said nozzle throat clearance ormachine direction position.

3. The process of regulating tensile ratio in paper during continuouspaper formation by the delivery of fibrous slurry onto a movingforaminous medium through an adjustable pressure nozzle having anapproach channel, a nozzle throat and a formation zone capable ofadjustment, which process comprises:

' (a) adjusting the nozzle throat clearance in the adjust able pressurenozzle to achieve an initial fibrous slurry velocity in the formationzone,

(b) adjusting the formation zone of the adjustable pressure nozzle toachieve an initial formation zone length,

(c) fixing the nozzle throat clearance and the formation zone length inmachine direction position, and thereafter (d) regulating the tensileratio of the paper during con tinuous paper formation by adjusting theconvergence angle in the approach channel without altering saidformation zone length or nozzle throat clearance.

4. An adjustable pressure nozzle within a headbox for a papermakingmachine for delivery of fibrous slurry to a moving foraminous medium;said pressure nozzle comprising a vertically converging rectangularpassage means such that the slurry passes through at least a backchannel, an approach channel, an angle channel, a nozzle throat, and aformation zone onto said moving foraminous medium; said passage meansdefined on its roof by a back channel roof, an approach channel roof, anangle channel roof, and a slice roof having a slice tip; said passagemeans being defined on its floor by a channel floor connected to anapron and by a section of said moving foraminous medium extendingbeneath and between the apron and the slice roof tip; said back channelroof having a downstream end connected to the headbox by expansionknuckle tension rods such that the downstream end is held upwardlyagainst an expansion knuckle connected to the upstream end of saidapproach channel roof, said upstream end of said approach channel alsocomprising a first approach knuckle which is connected to and pivotableabout a first approach knuckle pivot; the downstream end of saidapproach channel roof being pivotally connected to the upstream end ofsaid angle channel roof by a second approach knuckle which is connectedto and pivotable about a second approach knuckle pivot, and which isvertically adjustable by means of a connected approach adjustment jack,the downstream end of said angle channel roof being pivotally connectedto the slice roof by an outer throat knuckle which is connected to andpivotable about a throat knuckle pivot, and which is verticallyadjustable by means of a connected throat adjustment jack, said throatknuckle being adjustable in the machine direction by means of aconnected slice overhang adjustment jack and the slice roof tip beingvertically adjustable by a micro-jack means; the apparatus coacting suchthat the throat knuckle and slice root can be fixed in machine directionposition, by means of the slice overhang adjustment jack, after initialadjustment while the convergence angle to the approach roof and angleroof with respect to the channel floor remains adjustable.

5. An adjustable pressure nozzle for the delivery of fibrous slurry ontoa moving foraminous medium in a papermaking machine as defined in claim4 wherein the outer throat knuckle is an expansion knuckle.

6. An adjustable pressure nozzle for the delivery of fibrous slurry ontoa moving foraminous medium in a m 10 References Cited UNITED STATESPATENTS 4/1947 Ostertag et al l62214 5/1967 Holt 162-317X US. Cl. XR

